The field of the invention is systems and methods for magnetic resonance imaging (“MRI”). More particularly, the invention relates to moving MRI systems and methods for their use.
Functional magnetic resonance imaging (“fMRI”) provides high spatial resolution mapping of brain activation during various stationary tasks. Today, fMRI is always performed using stationary, earth-horizontal magnets. But the majority of humans and animals spend their active (i.e., non-sleeping) lives upright and moving about. The human nervous system has evolved to function during motion, and performance during motion is required for athletic tasks (e.g., hockey, baseball, gymnastics) as well as for common daily tasks.
Currently existing MRI is practiced with an MRI scanner in which the magnet, RF coil, and other structures of the scanner are fixed in position. If an object or a subject's body or body part is in motion while being scanned, the object, body, or body part must be small enough, or the amplitude of motion must be small enough, to restrict the motion to the confines of these MRI scanner structures.
Today, functional MRI scanning while a human subject is upright, at an arbitrary tilt angle with respect to vertical, moving significantly (e.g., walking, rotating), or some combination of these conditions is impractical or otherwise not possible because of the extreme confinement imposed by existing MRI scanners and—far more importantly—because of the powerful and confounding physical and physiological effects of the magnetic field, especially for large movements of the brain and body relative to the imaging system. As a result, the inability to perform functional MRI of vestibular function and other motion-related functions leaves that part of the human brain map a wholly blank slate.
Although MRI scanners with weak or very weak magnetic fields, such as those generated by permanent magnets or non-superconducting electromagnets, exist and may permit significant motion of an object or subject being imaged, the image quality of such scanners is inadequate for high quality anatomic or functional MRI.
There thus remains a need for an MRI system with a magnet system, whether including a superconducting magnet or permanent magnet, that is capable of imaging a freely moving body, body part, or object, such that studies of naturalistic motions and their associated neural activity can be performed.